The Heart, Coronary Circulation, Conducting System Flashcards
What is the only branch of the Ascending aorta?
The Coronary arteries
What are the origins of the left and right Coronary arteries?
They originate from the left and right cusps of the aortic valve, respectively
Wat is the anatomical position of the main stem of the left Coronary artery?
Main stem lies between the left auricle and the pulmonary trunk where it then enters the coronary sulcus
What are the branches of the left Coronary artery?
- Circumflex branch
- left marginal branch
- anterior inter ventricular branch ( left anterior descending branch)
What do the branches of the left Coronary artery supply?
- walls of the left atrium and left ventricle
- most of the inter ventricular septum and anterior part of the atrioventricular (AV) bundle
Where does the right Coronary artery main stem emerge from?
passes between the right auricle and the pulmonary trunk
What are the 3 branches of the right coronary artery?
- sino-atrial nodal branch
- right marginal branch
- posterior inter ventricular branch
what is supplied by the right Coronary artery?
- walls of the Right atrium and ventricle
- sinu-atrial node and the atrioventricular node
- posterior part of the inter ventricular septum
- small areas of the walls of the left atrium and left ventricle
where does the RCA anastomose with LCA?
anastomoses with the LCA in the coronary sulcus and the apex of the heart
where does the LCA anastomose with the RCA?
anastomoses in the coronary sulcus and posteriorly at the apex
What is the importance of the anastomoses between the coronary arteries?
The coronary arteries create a parallel circuit around the heart so if there is an occlusion then blood flow is not limited to a certain area of the heart
What does the anastomoses between the coronary arteries allow to happen?
In times occlusion it allows the operation of a Coronary Artery Bypass Grafting to take place. Uses the great saphenous vein to form the vessels from the ascending aorta hence bypassing the occlusion.
Which vessel does most of venous blood drain to in the heart?
the coronary sinus
What is the anatomical position of the coronary sinus?
lies between L atrium and L ventricle and drains into the Right Atrium
What are the 3 main veins of the heart? Which arteries are they associated with?
- great cardiac vein with the LAD
- middle cardiac vein with the Posterior inter ventricular
- small Cardiac vein with right marginal vein
What are the components of the coronary conducting system of the heart?
- SA node
- AV node
- Atrioventricular bundle of His
- Right and Left bundle branches
- Purkinje fibres
What is the anatomical position of the SA node?
In the right atrium near the opening of the SVC
What is the anatomical position of the AV node?
lies in between the entrance to the tricuspid valve and the coronary sinus
what is the only conductive route through the fibrous skeleton?
AV bundle of His
What is the function of Purkinje fibres?
They spread the electrical conduction through the ventricles
Describe how contraction occurs in the heart.
contraction is initiated by the SA node.
The SA node impulses the rhythm of the heart
conduction then passes down to the apex of the heart so that ventricular contraction is towards the atrioventricular valves
What effect does sympathetic innervation have on the heart?
- Increases heart rate
- increases force of contraction
what effect does parasympathetic innervation have on the heart?
- decreases heart rate
- decreasing the calibre of the coronary arteries
What innervates the heart sympathetically?
Sympathetic cardiac nerves from both sympathetic trunks
What is the parasympathetic innervation of the heart?
parasympathetic branches from both Right and left Vagus nerves
Where do sympathetic efferents return to from the heart?
their site of origin from spinal cord T1 to T4
What is the cardiac plexus formed of?
a mix of parasympathetic and sympathetic nerves
where is the cardiac plexus situated?
adjacent to the bifurcation of pulmonary trunk and trachea
What is the function of the cardiac plexus?
sends efferent and afferent branches to the SA node, AV node, cardiac musculature and coronary arteries
What is an inferior infarct and what does it cause?
- obstruction to the right coronary artery
- likely to cause arrhythmias
what is an anterior infract?
obstruction to the left coronary artery, specifically the LAD or anterior inter ventricular branch
What are the dangers of an anterior infarct?
Cause catastrophic loss of left ventricular function and the ischaemia may also lead to ventricular fibrillation= cardiac arrest
what is a lateral infarct?
obstruction of left circumflex artery
